In electrical interfaces, the contact surfaces are frequently made of metals or metal platings which are non-compatible. This non-compatibility is usually due to oxidation of one or more of the contact surfaces. As an example, the contacts may be made of silver, copper, tin or alloys of these metals. Due to exposure to the atmosphere, and especially under conditions of elevated temperatures which can be produced in electrical equipment, the surfaces of the metals oxidize. The oxidized metal surfaces are comparatively poor electrical conductors and a satisfactory electrical circuit is not obtained in the connector. One solution to this problem is to use noble metal platings, such as gold, on the contacting surfaces. However, the use of gold, even as an extremely thin plating, becomes cost prohibitive.
A further complication arising in an electrical contact between surfaces of differing metals or metal platings, is the difference in the differential movement of the surfaces by such as can be caused by thermal expansion of the dissimilar metals surfaces. Although a satisfactory contact may be effected at a given temperature when the temperature increases or decreases, the difference in thermal expansion between the metals results in a disparity between the dissimilar metals which causes an unsatisfactory electrical contact.
Thus, there is a need for an inexpensive, reliable electrical connector between contacting surfaces of metals which form oxides and also between dissimilar metals which have differing coefficients of thermal expansion.